1. Field of the Invention
The present invention generally relates to a quantization/inverse quantization circuit including a differential pulse code modulator (hereinafter referred to as a DPCM) which can be used in all video coder-decoder (hereinafter referred to as a CODEC) standards (i.e., JPEG, H.261, H.263, MPEG-1, and MPEG-2). More particularly, it relates to a quantization/inverse quantization circuit which can support a quantization/inverse quantization function suitable to a desired standard according to a process mode.
2. Description of the Conventional Art
The present invention relates to techniques of a quantization circuit used for video CODEC standards (JPEG, H.261, H.263, MPEG-1, and MPEG-2). The quantization of the video CODEC divides a discrete cosine transform (hereinafter referred to as a DCT) coefficient into quantization gaps by a quantization matrix, and then rounds it off to an integer value. On the contrary, an inverse quantization step multiplies a quantized value by a quantizer scale. A division step does not use a divider in the quantization step, but the division step uses an inverse number of a divisor and multiplies the inverse number. As a result, quantization and inverse quantization are achieved by using only a multiplier without using an additional divider. The quantization circuit is selected for all video CODEC standards and employed.
Since a conventional quantization/inverse quantization circuit is suitable to only one standard, it could not be used for other standards. Furthermore, to achieve a reconstruction mode processing, an additional inverse quantization circuit in addition to the quantization/inverse quantization circuit is needed, thereby requiring more hardware area. In addition, the conventional art does not include DPCM, so that it additionally includes an independent DPCM at its external part.